Dictionary.com
definitions

balkline

[bawk-lahyn]
noun
  1. Sports. (in track events) the starting line.
  2. Billiards.
    1. a straight line drawn across the table behind which the cue balls are placed in beginning a game.
    2. any of four lines, each near to and parallel with one side of the cushion, that divide the table into a large central panel or section and eight smaller sections or balks lying between these.
    3. a balk lying inside one of these sections.
    4. balk(def 11).

Origin of balkline

First recorded in 1830–40; balk + line1
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018